#include <stdio.h>
#include <math.h>

int main(){
    float integral(float (*)(float),float,float,int);
    float fsin(float);
    float fcos(float);
    float fexp(float);
    float a1,b1,a2,b2,a3,b3,c,(*p)(float);
    int n=20;
    printf("input a1,b1:");
    scanf("%f,%f",&a1,&b1);
    printf("input a2,b2:");
    scanf("%f,%f",&a2,&b2);
    printf("input a3,b3:");
    scanf("%f,%f",&a3,&b3);
    p=fsin;
    c=integral(p,a1,b1,n);
    printf("The integral of sin(x) is:%f\n",c);
    p=fcos;
    c=integral(p,a2,b2,n);
    printf("The integral of cos(x) is:%f\n",c);
    p=fexp;
    c=integral(p,a3,b3,n);
    printf("The integral of exp(x) is:%f\n",c);
}
float integral(float (*p)(float),float a,float b,int n){
    int i;
    float x,h,s;
    h=(b-a)/n;
    x=a;
    s=0;
    for(i=1;i<=n;i++){
        x=x+h;
        s=s+(*p)(x)*h;
    }
    return s;
}
float fsin(float x) {return sin(x);}
float fcos(float x) {return cos(x);}
float fexp(float x) {return exp(x);}